The Impact of Carbon Nanotube Length and Diameter on their Global Alignment by Dead-End Filtration

Dead-end filtration has proven to effectively prepare macroscopically (3.8 cm(2)) aligned thin films from solutionbased single-wall carbon nanotubes (SWCNTs). However, to make this technique broadly applicable, the role of SWCNT length and diameter must be understood. To date, most groups report the alignment of unsorted, large diameter (approximate to 1.4 nm) SWCNTs, but systematic studies on their small diameter are rare (approximate to 0.78 nm). In this work, films with an area of A = 3.81 cm(2) and a thickness of approximate to 40 nm are prepared from length-sorted fractions comprising of small and large diameter SWCNTs, respectively. The alignment is characterized by cross-polarized microscopy, scanning electron microscopy, absorption and Raman spectroscopy. For the longest fractions (L-avg = 952 nm +/- 431 nm, Delta = 1.58 and L-avg = 667 nm +/- 246 nm, Delta = 1.55), the 2D order parameter, S2D, values of approximate to 0.6 and approximate to 0.76 are reported for the small and large diameter SWCNTs over an area of A = 625 mu m(2), respectively. A comparison of Derjaguin, Landau, Verwey, and Overbeek (DLVO) theory calculations with the aligned domain size is then used to propose a law identifying the required length of a carbon nanotube with a given diameter and zeta potential.

Automated summary

Dead-end filtration is an effective method for preparing aligned thin films of single-wall carbon nanotubes. This study focuses on the role of SWCNT length and diameter in the alignment process. Films were prepared from length-sorted fractions of small and large diameter SWCNTs, and the alignment was characterized using various microscopy and spectroscopy techniques. The findings suggest a law that relates the length of a carbon nanotube to its diameter and zeta potential.